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(No Model.) 2 Sheets-Sheet 1.

G. BORGHARD.

' BOLT. No. 395,540. Patented Jan. 1,. 1889.

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N. VETEFLR Flluko-Lilhngnpher. Washington, D. C.

2 Sheets-Sheet 2.

(No Model.)

0. BORGHARD.

BOLT.

No. 395,540. Patented Jan. 1, 1889;

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vertical section of the door and lock.

NITED STATES PATENT rricE.

CHARLES BORCHART), OF DEIROIT, MlUl'llGAN.

BOLT.

SPECIFICATION forming part of Letters Patent No. 395,540, dated January 1, 1889.

Application filed May 28, 1888. Serial No. 275,267. (No model.)

To all whom it may concern:

Be it known that I, CHARLES .BORCIIARD, a citizen of the United States, residing at De troit, in the county of lVayne and State of Michigan, have invented certain new and useful Improvements in Locks for Foldin g Doors, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to new and useful locks such half every time the principal half 3 of the door is locked or unlocked, thereby saving the trouble of operating the locking device of the supplementary half of the door.

My invention consists in an automatic locking device for the supplementary half of the door, which firmly holds that half in closed position when the principal half is closed, and which automatically unlocks when such principal half is open ed, all as more fully hereinafter described. and shown in the accompanying; drawings, in which Figure 1 a perspective view of a folding door provided with my improved lock. Fig. 2 is a detached perspective view of the lock with the corner of the door to which it is secured. Fig. 3 is a vertical section of the door with the lock in side elevation. Fig. l isa Fig. 5 is a detached perspective of the casing-of the lock. Fig. 6 is a detached perspective of the back plate of the casin Fig. 7 is a detached perspective view of the bolt mechanism of the lock. Fig. 8 is a detached perspective of the stop and keeper of the bolt.

A is a casing.

r are flanges on. the casing for sccurin g it in position on the upper inner corner of. the supplementary door.

(I is a bolt slidingly secured in the casing.

D is a lateral curved arm on the inner end of the bolt.

E a rctractirig-spring ot the bolt, which normally keeps the bolt retracted within. the casing.

F is a crank-shaft journaled in bcarin a l), transverse with the casing.

G is a crank formed on the inner end of the crankshaft within the casing and adapted to engage into a notch, 0, formed in the arm D of the bolt. H is another crank formed in the crank-shaft outside the casin g, preferably integrally with the crank-shaft.

I is a back plate adapted to fit into the opening back of the casing to retain the parts therein in position, and this back plate is provided with a guide-arm, (Z, which engages into an aperture, 6, formed in the rear end of the arm of the bolt to guide the boltin a straight line.

To secure the back plate to the casing, I provide the casing with a few burrs, f, which in peening over are adapted to secure the back. plate.

K is the keeper of the bolt secured to the door-j amb in suit-able relation to the bolt, and L is a stop formed integrally with the keeper K.

M is a suit-able lock secured on the principal halt of the door.

In practice, the parts being constructed and arranged substantially as described and shown, the lock is secured to the upper eor ner of: the supplementary door, and in such re lation to theprincipal door that in closing such latter door it strikes the crank ll and thereby actuates the bolt, through the medium oi? the parts described, to project into its keeper against the action of the tension-spring, which, in opening the door, immediately retracts the bolt into its normally-retracted position. The crank ll is sufficiently curved forward into the path of the principal door to impart to the crank H the necessary amount of motion to project the bolt; and to prevent the door from being marked by the impact with such crank I provide the principal door with the striking-plate N. Thus it will be seen that if the lock M of the principal door is closed the supplementary door is also firmly locked automatically, and if the principal lock is unlocked the supplementary part of the door is unlocked automatically. The advantage of myconstruction if applied to cabinets, book-cases, closets, &c., where generally folding doors are applied, or to double windows, is obvious, as in such applications the discomfort and trouble usually experienced of manipulating ordinary bolts, which are often out of the reach of the operator, and the difficulty of operation, are entirely avoided.

\Vhile l have specified some of the applications of my invention, I do not intend to confine myself to such applications alone. The same locking device described may be applied to the lower corner of the door as Well, especially where the doors are of great height.

\Vhat I claim as my invention is-- 1. In a lock for folding doors, the combination of the casing A, provided with the flanges B, the sliding bolt 0, the curved arm D, provided with the notches c e, the retractingspring E, the crank-shaft F, the crank G, engaging into the notch c, the crank H, formed on the crank-shaft F, outside the casing, and

the back plate I, provided with the guide-arm d, engaging into the notch c, the parts being arranged and constructed to operate substantially as described.

2. As a new article of manufacture, a lock for double doors consisting of an inclosing frame or casing, a sliding bolt secured therein, a spring arranged to normally retract the bolt, a crank-shaft journaled in the casing, a crank secured upon said crank-shaft Within the casing and engaging with the bolt, and a crank on said crank-shaft outside the casing, substantially as described.

In testimony whereof I affix my signature, in presence of two witnesses, this 19th day of May, l 888.

CHARLES BORCHARD.

\Vitnesses:

P. M. HULBERT, JOHN SCHUMAN. 

